Unit 5

1. Read and translate the text how to select building materials that resist moisture

Some materials used in houses are more resistant to moisture, water, flooding, and mold than other materials. Selecting materials that are more suited for contact with floodwaters or water for three days or more without significant damage is important in areas where flooding occurs and hurricanes are possible.

Choose materials based on location, their compatibility with other types of materials, and on how the total components or systems (wall, floor) drain and dry. Although some materials resist floodwater and moisture damage, they may also inhibit drying. Resistance to moisture combined with the ability of the total component to dry is an important consideration.

The following is a partial listing of materials that may resist water and flooding. Before making a selection, consult with the manufacturer about the item's purpose. This listing is not an endorsement of any one product or material. Other materials may be suitable. Check building code requirements.

Moisture-Resistant Flooring Materials

• Concrete materials such as concrete tile, pre-cast concrete, or latex or bituminous formed-in-place can be colored, polished, and sealed.

• Non-porous stone, slate, or cast stone with waterproof mortar.

• Clay tile, quarry tile, terrazzo, or ceramic tile.

• Rubber sheets or tiles.

• Naturally decay-resistant wood subflooring (redwood, cedar, some oaks, bald cypress) or steel for structural members. However, wood can warp. Unless the finished flooring is removed immediately to allow the subfloor to dry, it may become damaged and moldy.

• Solid plastic lumber (may inhibit drying).

• Waterproof mortar or adhesives (may inhibit drying of the subfloor).

• Mastic or silicone, epoxy, or polyurethane formed-in-place.

Moisture-Resistant Wall Materials

• Steel with waterproof applications (coated to resist corrosion); steel studs, beams, and sill plates.

• Solid naturally decay-resistant wood for structural components.

• Cement board.

• Brick.

• Cast stone with waterproof mortar.

• Structural glazed clay tile.

• Ceramic veneer or ceramic wall tile - mortar set, porcelain.

• Concrete.

• Glass blocks or glass panels (may break).

• Plaster with metal lath.

• Natural solid or veneer stone with waterproof grout.

• Artificial non-absorbent solid or veneer stone with waterproof grout.

• Corrosion-resistant metal, metal clad, and vinyl window frames; solid wood window frames in good condition may survive well but are subject to swelling and warping. Interior metal or fiberglass doors. Use impact resistant glass.

• Corrosion-resistant metal exterior doors.

• Rubber mold epoxy polyamide adhesive or latex hydraulic cement.

• Exterior fiber-cement, vinyl, or aluminum siding, brick, or concrete. Lap siding generally permits drying. Brick must be installed correctly and drainage provided so that water and moisture vapor behind the brick can drain and dry. Reinforced poured concrete is strong and has fewer seams than concrete block. Seams may allow water entry.

• Sheathings must be able to dry. Plywood sheathing is strong although it may dry slowly. Oriented strand board (OSB) may swell.

If wallboard must be used, use non paperfaced gypsum wallboard, water resistant fiber-reinforced gypsum wallboard or panels, or cement board. These products may provide more resistance to moisture and mold than regular dry wall faced with paper. Research has indicated that quick-setting joint compound and fiberglass tape may withstand water and flood events better than regular drywall joint compound and paper tape.

Coverings and coatings should allow drying in at least one direction so that interior wall and floor systems can quickly drain and dry. More testing of components or wall systems in actual flood situations and on individual materials is needed.

Even with water-resistant materials, some damage may occur if a home is flooded. Clean up is necessary and painting and repairs may be needed.

When materials such as tile and plywood are used together, drying time may be reduced. However, water may be trapped behind and under surface materials. Before selecting material combinations for walls and floors, consider length of drying time if water were to be trapped inside the combinations, or in the wall or floor systems. The combination should allow drying in at least one direction. Consider the following questions before you make a final decision. Which way can water drain and dry out? Will the surface material have to be removed from the combination to allow drying? Is the surface material easy to remove to allow drying time?

Key words: moisture, water-resistant materials, moisture damage, drying, waterproof application